Slow performance on large assemblies

I am using solid works 2012 on large files. Previously my system was 16 GB. I have updated that to 32 GB. During working on large files it uses only 4 GB. Updating RAM does not helped me.

Please suggest regarding Good performence of solidworks during on large assembly file.(For giving a single mate in assembly, it is taking too much time.)

SolidworksAssemblies